1. Field of the invention:
This invention relates to hydroxyl-containing polymers and is particularly concerned with an improved process for producing from saturated or substantially saturated hydrocarbon polymers of generally high molecular weight, relatively low molecular weight curable, hydroxyl-containing liquid saturated hydrocarbon prepolymers, and with production of such low molecular weight curable prepolymers
Hydroxy-containing polymers such as hydroxy-terminated liquid prepolymers, can be cured or chain extended to produce highly stable elastomers having many applications. Thus, in our copending application Ser. No. 301,794 filed Oct. 30, 1972, and now U.S. Pat. No. 3,919,172, there is disclosed chain extension of hydroxy-terminated liquid polymeric polyols with a tetrafunctional organic dianhydride, such as pyromellitic dianhydride, for production of stable, elastomeric polymers, e.g., useful as binders for solid propellants.
2. Description of the prior art
In U.S. Pat. No. 3,312,744 there is disclosed a process for producing hydroxyl functional polymers of low molecular weight in the 200-400 range by subjecting long chain nonfunctional olefinic polymers or copolymers, having unsaturation in the primary chain, to ozonization, followed by reduction of the ozonide with lithium aluminum hydride, to yield the above-noted short-chain hydroxy functional polymer.
However, it is noteworthy that the process of the above patent is limited in its application to use of highly unsaturated polymers and copolymers, that is olefinic polymers having a plurality of olefinic linkages in the primary chain, as parent polymer, and produces unsaturated hydroxy functional polymers having a low and relatively narrow molecular weight range.
U.S. Pat. No. 3,392,154 discloses reaction of unsaturated olefin structures of the monoolefin-diolefin copolymer type, with ozone, followed by decomposition of the resulting material to produce saturated hydrocarbon chains containing hydroxyl groups at each end, carboxyl groups at each end, or a mixture of terminal hydroxyl and carboxyl groups. However, here again, the process is limited to use of an unsaturated rubbery copolymer as starting material, and the resulting hydroxyl-containing material is limited to a functionality of only about 2, since only functional end groups are present.